broadband: anything up to full screen (1290 x 1024px is prob most popular size at min)
Pano size 6000 x 3000px (eq pano) seems to be best size/quality compromise for a qtvr pano around 1-2mb
Dial up: 400 x 300 viewer optimum, 600 x 400 max
pano size 1200 x 600 - 1600 x 800px (eq pano)